Beebiz is absolutely right; and ducks will try to breed with almost anything on their level (of height, that is). Mr.Flapper is a well-known Pekin with a small harem of Muscovies and friends, you should check out all the great pics.

Yea only muscovey crosses are steril. Other ducks can cross breed and they wil be fertile .

I was told and read in some books that if a male muscovey breeds with a muscovey hen that he will never breed with any other breed of duck . I dont know if that is true . Like i said a farmer told me that and i read it in a few books i have so i duno how true that is